A sounding reference symbol (SRS) is a symbol that is sent by a user terminal to a base station and that is used for detecting a status of a channel between the user terminal and the base station. Generally, the SRS is a last symbol of an uplink subframe. An uplink subframe includes a plurality of symbols, and a symbol includes a plurality of pieces of sampled data. In a distributed base station architecture of BBU-RRU (baseband processing unit-radio remote unit), an RRU receives, by using a large scale antenna array, SRS sampled data sent by the user terminal, and sends, by using an optical fiber, the SRS sampled data to a BBU for processing.
It is found in practice that the RRU usually receives a large amount of SRS sampled data by using the large scale antenna array. For example, when the large scale antenna array includes 256 antennas, the RRU receives, in parallel by using the large scale antenna array, 256 pieces of SRS sampled data sent by a user terminal. In actual application, the radio remote unit needs to send, at the same time, the large amount of SRS sampled data received in parallel to the BBU for processing, and therefore, excessively high bandwidth is required for transmitting the SRS sampled data by the radio remote unit, and a relatively high requirement is imposed on network deployment.